It has recently become evident that in malignant neoplasms components are present which are immunologically identical to embryonic constituents, but not in normal adult tissues. The proposed research project is designed to investigate specific human embryonic components and their relationship to malignant neoplasms. Using immunological techniques and methods of purification and identification of proteins and glycoprotein complexes, an attempt will be made to characterize specific embryonic components which are present in human malignant neoplasms. In addition to known components present in both carcinomas and embryonic tissues, preliminary studies in our laboratory indicate that other unique common antigens exist. The identification of unique tumor associated antigens may provide the basis for an early detection of malignancy.